The AC control panel in my 1997 Suburban.

Hello everyone. When my left-most dial is on high speed, it works for a while, blowing really hard. Then all of a sudden, it blows less intense. After a few minutes, it goes back to blowing really hard. The situation constantly repeats itself. The other three speeds work fine.

Any help on what's wrong would be appreciated. Ted

 

kinda hard to say without testing.
system operation is as such:
power is supplied to the high speed blower relay (on the hvac case) at all times by the ac maxi fuse.
the heater ac fuse provides power in run to the blower switch/****...when turned to high... the power flow to the high speed blower relay to close the relay and give full power to the blower motor.
the proper way to test is to measure voltage drops across the components to find the loss of voltage. sounds like you are dealing with a resistance problem....bad connections, worn relay, worn blower motor brushes could also cause this problem

 

Thanks tech2. I own my 1997 Suburban from new. Now that it is 23 years old, things are starting to go wrong. I can't complain, it's been reliable all these years.

I am a newbie when it comes to repairing auto electronics, so here goes...
where are both the high speed blower relay (on the hvac case) and the ac maxi fuse you refer to? I intend to follow the leads you provided to solve my problem.

Also, can it be the blower motor resistor? I don't think so, because I figure if the resistor was bad, it wouldn't work at all. Maybe I'm wrong.

Being retired and locked down, I have nothing but time on my hands, so I will get to work hopefully this week. Ted

 

the blower motor resistor is bypassed when in high... so nope, it can't be the problem.
the hs relay is under the instrument panel on the hvac case
the maxi fuse would be in the underhood fuse box

 

Thanks tech2 for that info. This will be my project for the weekend. Ted.